Integrated circuits have become important components in most electronic and electromechanical devices. There is considerable revenue generated from the sales of integrated circuits, and it is desirable in the industry to obtain intelligence on an integrated circuit in order to be competitive. As such, the reverse engineering and analysis of integrated circuits have become important aspects of business intelligence.
It is generally desirable to gain competitive intelligence on a simple circuit or only one function within a multifunction chip. An integrated circuit generally includes hundreds of thousands or more components interconnected by a complex network of vias and metal lines. Consequently, it is difficult and time consuming to isolate a circuit or structure of interest used to perform a particular function, or to determine whether the integrated circuit includes the circuit of interest.
Prior art reverse engineering methods are generally directed to methods for determining whether an IC (Integrated Circuit) includes a specific known structure.
Referring to FIG. 1, shown is a flowchart of a conventional method of locating a structure of interest in an integrated circuit. At step 10, the integrated circuit is prepared for analysis. For example, the integrated circuit is decapsulated from its shell. The integrated circuit is then deconstructed (step 12) in a manner well known in the art to expose a first metal layer. The deconstruction of the integrated circuit may be a mechanical process, such as polishing for example or a chemical process such as wet or dry etching. After exposure of a first metal layer, the integrated circuit is mounted on a precision stage and the precision stage is maneuvered to permit images of the first metal layer to be acquired (step 14). If another layer exists (step 16) the integrated circuit is further deconstructed to expose the other layer (step 18) and the step of mounting the integrated circuit on the precision stage and maneuvering the precision stage to acquire the images of that layer (step 14) is repeated. The manner in which the images are acquired depends on the component size of the integrated circuit. If the components are large enough, an optical microscope and an optical imaging system may be used for that purpose. If the components are too small for optical imaging, a scanning electron microscope is normally used to acquire images of the exposed components of each layer.
After images of all the layers are acquired, the images of each layer are mosaiced together combined to form image mosaics (step 20). Many image mosaic methods are known and well understood by those skilled in the art. Once the respective image mosaics are formed, the image mosaics are overlaid and aligned to permit a reverse engineering of the integrated circuit (step 22). After image preparation is complete, a user identifies an area of interest for locating the structure (step 24). This is accomplished on the basis of known information on the configuration and function of the structure. The user then searches the image mosaics for the structure (step 26). For example, the structure may consist of a few dozen components. However, the integrated circuit may have hundreds of thousands of components or more. Such a search may be quite time consuming. If the user locates the structure of interest (step 28) a report is prepared (step 30) and the process ends. If not, the user determines (step 32) whether all search options have been exhausted. If so, the process ends without success. If not, the user identifies another area of interest (step 34) and steps 26, 28, and 30 are performed or steps 26, 28, 32, and 34 are repeated depending on whether all options have been exhausted.
The above described method requires the deconstruction and imaging of an entire integrated circuit to locate a specific structure of interest, this can be very time consuming and expensive.
Another reverse engineering method is disclosed in U.S. Pat. No. 6,496,022 assigned to IBM, which describes a method for locating a known structure by comparing an optical emission pattern of the IC under test with reference patterns. Such an approach to reverse engineering requires that the structure be known and reference data on the structure be available.
Thus, there is a need for a method and system for locating a structure of interest in an integrated circuit, which permits the structure of interest be located more efficiently and for a lower cost. Moreover, there is a need to determine whether the integrated circuit includes a structure of interest when no reference data is available on the structure of the circuit of interest.